Battery charger



FIG. 1 is a perspective view showing the new design for a battery charger;

FIG. 2 is a front view thereof, the back view being a mirror image of the front view shown;

FIG. 3 is a side view thereof, the opposite side view being a mirror image of the side view shown;

FIG. 4 is a top view thereof; and,

FIG. 5 is a bottom view thereof.

The broken lines in the drawings are shown for illustrative purposes only and form no part of the claimed design. 

CLAIM The ornamental design for a battery charger, as shown and described. 